The other disorder was chronic granulomatous diseasewhich is also X-linked and yielded to positional cloning in Discovery and subsequent analysis of the gene mutation that results in the clinical disorder led to the discovery of the encoded protein, dystrophin. This coinage set a precedent for the naming of proteins discovered by positional cloning of human disease genes: The largest proteins in muscle then known were nebulin kD and titin over kD.
Reporting in the current issue of Science, researchers describe how they used CRISPR technology to edit a naturally occurring genetic flaw that causes a version of Duchenne muscular dystrophy in dogs. The discovery might hold the key to helping children with Duchenne MD, the most common form of muscular dystrophy.
MD is a group of incurable genetic disorders that cause progressive muscle degeneration.
Duchenne MD primarily affects boys and usually arises in early childhood. Historically, most boys did not survive beyond their teens, but more are living into their 30s these days, according to the Muscular Dystrophy Association. Duchenne is caused by a mutation in a gene that produces a critical protein called dystrophin.
Without it, muscles throughout the body -- including the heart and diaphragm -- break down over time. To do that, researchers have been studying gene therapy. But with Duchenne MD, Olson said, there is a hurdle to replacing the defective gene with a functioning one: So Olson and his team took a different approach.
The researchers treated four dogs that carried the most common mutation seen in people with Duchenne MD -- affecting a location on the dystrophin gene called exon The effects were not uniform. In some muscle, dystrophin was produced at 3 percent of its normal level.
But in the heart and diaphragm, the protein was restored to 92 percent and 58 percent of normal, respectively. Olson put the increases in dystrophin levels in perspective: There is a drug for Duchenne MD -- called Exondys 51, and approved in the United States in -- that can be used in a minority of patients who have a mutation in exon It has been shown to restore less than 1 percent of dystrophin in skeletal muscle after one year, Olson pointed out.
The findings are "very encouraging," said Dr.
But they are also very early, she pointed out. There are two main theoretical safety concerns, according to Olson: So far, there have been no signs of that, the researchers said.
Often, the agency says, there is no family history of the disease; instead, mutations spontaneously occur in the dystrophin gene.Muscular dystrophy is a group of diseases or disorders that weaken the muscles in the body over time.
The progressive weakness can make it difficult for the person to do everyday tasks such as. A study of Duchenne muscular dystrophy has shown an approximate prevalence of the disease among schoolboys to be 1 in Fifty-four families were available for genetic studies.
In 19 families there were further affected cases and in 34 families the index patients was an isolated case.
Duchenne muscular dystrophy is caused by mutation in the dystrophin gene on the X metin2sell.comphin is associated with a large oligomeric complex of sarcolemmal glycoproteins, the dystrophin-glycoprotein complex, which spans the sarcolemma to provide a link between the subsarcolemmal cytoskeleton and the extracellular matrix component, laminin ().
Study Guide Fascioscapulohumeral Muscular Dystrophy Key Points: Facioscapulohumeral (FSH) muscular dystrophy is a progressive disease of skeletal muscle that primarily affects the muscles of the face and shoulder girdle. Duchenne muscular dystrophy (DMD) is a condition found almost exclusively in boys.
The disease is characterized by muscle weakness which begins to appear at a young age and progresses rapidly. A stem cell therapy improved the heart function, walking capacity and survival of mice with Duchenne muscular dystrophy, a study reports.
The treatment involves what scientists call cardiosphere-derived cells, or CDCs.